© Photo copyright Geoff York/Polar Bears International
4/17/2017 11:47:22 AM
Searching for Polar Bears in Alaska's Chukchi Sea
While on my way home from installing cameras to monitor polar bear dens in the central part of Alaska’s Southern Beaufort Sea, my phone rang. It was a colleague from the U.S. Fish and Wildlife Service. They needed an extra hand for their multi-year program that monitors polar bears in the Chukchi Sea, a project I helped launch when still working for the U.S. Geological Survey in 2008. My mind answered in the affirmative, but I said I would need to check my calendar, check with my team at Polar Bears International, and check with my wife before I could confirm. Luckily for me, I had a flexible schedule for the dates needed and all were supportive.
As strange as it may seem, looking down at polar bear tracks through the side window of a helicopter as we bank to inspect their quality and direction; enjoying the active flying required to follow those tracks (we rarely fly straight or level); approaching a newly sedated polar bear; and working with a team to collect a variety of samples and measurements while standing on frozen sea ice is all normal to me—it’s what I do.
The Chukchi Sea crew from left to right, Jonathan Larrivee (pilot), Michelle St Martin (U.S. Fish & Wildlife Service Alaska), Riley Wilson (veterinarian), Geoff York (Polar Bears International), and Ryan Wilson (U.S. Fish & Wildlife Service Alaska).
This marked my 19th polar bear capture season over 20-plus years of working in the Arctic. While the flying is challenging, the weather daunting at times, and the logistics of the work complex, the USFWS has a great team leading the effort, so I can plug in, focus on my tasks, and take a rare few days to truly be in the moment and fully in polar bear habitat. Following a protocol review with wildlife biologist and field program lead Michelle St. Martin, we began our work, led by USFWS wildlife biologist Ryan Wilson and Anchorage veterinarian Riley Wilson.
Remote field work
A look at our daily flight paths suggests that we’re working in the middle of nowhere. The middle of the Chukchi Sea, however, is the middle of everywhere for this population of polar bears. While 2016 and now 2017 continue to break records for sea ice loss across the Arctic (in both extent and volume), this region experienced cold temperatures over the winter, and the sea ice we encountered appeared of average to young age and thickness. While the neighboring Southern Beaufort Sea has seen dramatic changes in sea ice extent, coupled with a 40% decline in that polar bear population, the Chukchi bears appear to be faring better, at least for now.
Map showing the crew's flight patterns during the recent Chukchi Sea research. Although it may seem like the middle of nowhere, it's the middle of "everywhere" for this population of polar bears. Map courtesy of BJ Kirschhoffer/Polar Bears International.
Information generated from the USFWS-led project has already been used to understand the distribution and habitat use of the region’s polar bears, including the overlap of those habitats with planned oil and gas lease activity (Wilson et al. 2014). The first four years of data (2008-2011) provided insights on the population’s ecology. It suggests that sea ice loss in the region up to 2011 has not yet resulted in negative effects on the physical stature, body condition, or reproduction of the Chukchi Sea population (Rode et al. 2014a). It also suggest that the Chukchi Sea bears are currently more productive than the Southern Beaufort Sea population, which is shared with Canada.
USGS-led analysis (Rode et al., 2015) also showed that the number of polar bears from the Chukchi Sea population spending summer on shore has nearly doubled, and that the bears are spending 30 days longer on land compared with data from 1986-1995. The increased use of land may reduce the ability of polar bears to access their preferred ice seal prey ahead of the long winter season, potentially leading to increased nutritional stress and ultimately population declines.
Our team was lucky this year. In 12 days afield, we were able to fly on nine, which is unusual in the Arctic. In that time, we captured 28 bears, most of which had never been captured before.
We take a variety of measurements from every bear handled, including weight. We also take several samples to assess overall health, much like our annual physicals. And we mark all bears with a lip tattoo and ear tag with a matching number so they can be identified if captured again. A few adult females are fitted with satellite tracking collars to help biologists like Ryan better understand both general movements and habitat use over time. Working alongside an experienced veterinarian like Riley (he doubles as the vet for the Alaska Zoo) also sped up our time with each bear; collecting samples like blood were easy for him.
Scientists work quickly to obtain measurements and samples while the bear sedated. This data helps them understand the health and condition of the population. Photo copyright Geoff York/Polar Bears International.
Over the short time we were out on the ice, spring seemed to be starting a little early as temperatures rose from a start around -5 F on arrival to + 36 F on departure. To the south, satellite imagery showed the Bering Sea ice breaking up rapidly, and we had both more and wider leads to cross each successive day to reach the “bear zone”—this year some 60-90 miles offshore. We also started to see new life in the forms of migratory birds heading North as early as March 27th, both eiders and murres.
The Chukchi Sea is a dynamic place, constantly challenging our collective abilities to understand the region. Warming temperatures and increasingly active sea ice only further complicate matters, creating both physical obstacles and allowing more moisture into the air and increasing the likelihood of both snow and fog events. As the Arctic changes, long-term studies like this will help us understand how polar bear populations are responding, which will aid in their conservation.
Our team left the USFWS base camp feeling fortunate to have had the opportunity to work on such an amazing animal in such a uniquely beautiful place, thankful for the good weather and strong teammates, and grateful to the larger team at the USFWS that keeps this important work moving forward.